Process for the fluorination of boron hydrides

ABSTRACT

A process for fluorination of borohydride salts including providing a reaction medium comprising HF and a superacid. A borohydride salt compound is added to the reaction medium. The borohydride salt is reacted with the reaction medium under conditions to form a fluorinated borohydride salt. In addition, reactor vessels may be provided for reacting the HF, superacid additive and borohydride that are fabricated from materials resistant to superacid compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

The subject matter of this invention is related to U.S. patentapplication Nos. Ser. 10/655476, filed on Sep. 4, 2003 issued as U.S.Pat. No. 7,311,993 on Dec. 25, 2007 ; Ser. No. 10/924293, filed on Aug.23, 2004 issued as U.S. Pat. No. 7,348,103 on Mar. 25, 2008 ; Ser. No.11/372907, filed on Mar. 10, 2006, and Ser. No. 11/197478, filed on Aug.5, 2005. The disclosure of the previously identified patent applicationsis hereby incorporated by reference.

The present invention is directed to methods for fluorinating boronhydride compounds.

BACKGROUND OF THE INVENTION

Fluorinated boron hydride anions are weakly coordinating anions and havebeen used as electrolytes and as catalytic components, particularly toenhance the catalytic activity of metal cations finding use in a varietyof reactions.

The substitution of borohydrides, including polyhedral closo-boranes andcloso-carboranes with fluorine to various degrees has previously beenafforded by employing a number of methods. For example, the directfluorination of these exemplary boron hydrides with elemental fluorine(F₂) have been reported and readily provides highly fluorinated andmixtures of partially fluorinated products. N—F fluorinating agents havealso been employed in obtaining mixtures of partially fluorinatedproducts. N—F fluorinating agents suffer from the drawback that they areoften accompanied by difficulties associated with impurities formed bythe participation and undesirable substitution of the solvent. Thefluorination methods listed above, while capable of providing partiallyfluorinated products, all suffer from the drawback that they typicallyproduce mixtures of products with various isomers and relatively wideranges of degrees of fluorination.

HF has also been utilized to fluorinate borohydrides. Reactions ofB₁₂H₁₂ ²⁻ salts and monocarboranes with HF typically provide anadvantage in giving rise to products with narrow ranges for degrees offluorination. The degree of fluorination is progressive throughselective, well-established stereochemistry and may be controlledprimarily by varying the reaction temperature such that B₁₂H₁₂ ²⁻ isreported to provide the substitution of only six fluorine atoms at150-210° C. and monocarboranes are reported to provide the substitutionof only 3-4 fluorine atoms in the same temperature range. Additionalfluorine atoms can be substituted but under considerably more forcingconditions. These conditions are undesirable for industrial processesbecause the critical temperature for HF is 188° C. Such high temperatureHF is damaging to equipment and dangerous to handle.

Another method for fluorination of boron compounds includes U.S. Pat.No. 3,551,120, which discloses boron compounds of the formula M_(a)(B₁₂H_(12−y)X_(y))_(b) where M is a cation having a valence of 1-4, and(B₁₂H_(12−y)X_(y)) is a group which forms a divalent anion in an aqueoussolution. The term M represents hydrogen, ammonium, and metal cations,e.g., groups I, II VIII, IIIb and so forth. X represents halogen, (F,Cl, Br, and I), carboxyl, nitro, nitroso, sulfonyl, and so forth.Example 1 shows the formation of Cs₂B₁₂H₇F₅ by effecting fluorination ofCsB₁₂H₁₁OH in anhydrous HF. The temperatures utilized by this processare undesirably high in that the temperatures are above the criticaltemperature for HF.

U.S. Pat. No. 6,180,829 discloses metal compounds of polyhalogenatedheteroborane anions of the formulaM[R_(a)ZB_(b)H_(c)F_(d)X_(e)(OR″)_(f)]_(k) where M is a cation having avalence of from 1-4, e.g., an alkali or alkaline earth metal cation, Rtypically is a halogen or an alkyl group, Z is C, Si, Ge, Sn, Pb, N, P,As, Sb, and Bi; X is a halide and R″ is a polymer, hydrogen, alkyl andthe like. The subscripts represents integers. Example 2 shows theformation of the polyfluorinated monocarborane anion from amonocarborane hydride wherein CsCB₁₁ H₁₂ is reacted with a mixture of HFand 10% F₂ in N2. CsCB11F11H was recovered as a white solid. Significantcluster decomposition occurred during the fluorination, and yields were50-60% at these loadings. U.S. Pat. No. 6,448,447, acontinuation-in-part of U.S. Pat. No. 6,180,829 and others, discloses inExample 11 the formation of K₂B₁₂F₁₂ (1 g) by the continuous addition ofa fluorine/nitrogen gas phase to a suspension of K₂B₁₂H₁₂ in HF. Thisprocess suffers from the drawback that the distribution of fluorinatedproducts is undersirably broad. In addition, the process utilizesexpensive reagents, such as F₂.

Knoth et al, Chemistry of Boranes, IX. Fluorination of B₁₀H₁₀ ⁻² andB₁₂H₁₂ ⁻² Inorganic Chemistry, Vol. 2, No. 2, February 1964 disclose thepreparation of highly fluorinated dodecaborates, by (a) effectingfluorination with anhydrous HF alone to a composition up to B₁₂F₆H₆ ²⁻,and (b) effecting the direct fluorination of a 5 wt. % B₁₂H₁₂ ²⁻potassium salt by contacting the salt with F₂ in the presence of water(under these conditions, the HF concentration is never >10% and thus theHammett acidity, H_(o) remains >0 throughout the fluorination). Thereaction when conducted in the presence of water was difficult to run tocompletion as evidenced by the use of a 5-fold excess of fluorine. Inthe end, a low yield (32%) of a hydroxy substituted fluoroborate,B₁₂F₁₁(OH)²⁻, was obtained rather than the desired fluorine substituteddodecaborate.

Solntsev, et al, Stereochemical Aspects of the Fluorination of theB₁₂H₁₂ ⁻² Anion, Russian Journal of Coordination of Chemistry, Vol. 23,No. 6, 1997, pp 369-376, disclose that the reaction of supercritical HFwith K₂B₁₂H₁₂ at 600° C. generates the fully fluorinated anion.Significant decomposition was observed and yields of only 25% wereobtained under these conditions.

A stoichiometric oxidative fluorinating agent, antimony pentafluoride(SbF₅), has been employed in the fluorination of borohydrides, includingo- and m-carboranes. The SbF₅ utilized in the fluorination ofborohydrides previously known acts as a stoichiometric oxidativefluorinating agent, wherein this role of SbF₅ is well documented. Theuse of superacids, apart from HF alone, in aiding the fluorination ofborohydrides is not known in the art.

Thus, what is needed is a process that provides selective and controlledfluorination of borohydrides with facile, high-yielding synthesis offluorinated boron compounds of narrow and controlled degrees offluorination under reaction conditions that are industriallypracticable. The present invention provides these advantages as well asother related advantages.

The disclosure of the previously identified U.S. Patents is herebyincorporated by reference.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method for reacting at least oneborohydride salt with anhydrous hydrogen fluoride (HF) and at least onesuperacid additive to affect the conversion of B—H bonded centers to B—Fbonded centers in a controlled and selective manner by varying reactionconditions such as temperature, concentration, superacid additivecomposition, observance of well-established superacidic HF norms, andreactor materials of construction. Super Acid “SA” is defined as acompound or mixture of compounds capable of having an acidity oractivity (e.g., enhancing the ability to add F to the borohydrideprecursor) in anhydrous HF that is equal to or greater thansubstantially pure HF. This invention is efficient when relativelynon-oxidizing superacid additive, such as boron trifluoride (BF₃),tantalum pentafluoride (TaF₅), among others, are employed. If desired,the superacid additive can be mixed with another acid that is capable offorming an SA, or the HF can be combined with at least one other acidand combined with superacid additive.

One aspect of the invention includes a process for fluorination ofborohydride salts including providing a reaction medium comprising HFand at least one superacid additive. A borohydride salt compound isadded to the reaction medium. The borohydride salt has the followingformula:M_(a)[R_(b)Z_(c)B_(d)H_(e)F_(y)]_(k)wherein M is a cation having a valence from 1-4; R is selected from thegroup consisting of a halogen group, hydroxyl group, amino group, nitrogroup, alkyl group, alkoxy group, perfluoroalkoxy group, phenyl groupand combinations thereof; Z is selected from the group consisting of C,Si, Ge, Sn, Pb, N, P, As, Sb, Bi and combinations thereof; B is boron; His hydrogen; F is fluorine; a is 1 or 2; b is an integer from 0 to 11, cis 0 or 1; d is an integer from 5 to 12; e is an integer from 1 to 12;and y is an integer from 0 to 11; k is 1, 2, or 3. The borohydride saltis reacted with the reaction medium under conditions for formation of afluorinated borohydride salt having the formula:M_(a)[R_(b)Z_(c)B_(d)H_(e−n)F_(y+n)]_(k)wherein n is an integer from 1 to e. The fluorinated borohydride formedmay also include a degree of fluorination (i.e., [y+n]) of equal to orgreater than 5.

Another aspect of the invention comprises a process for fluorination ofborohydride salts including fluorinating a borohydride salt compound inthe presence of a superacid and HF in a reactor vessel fabricated from amaterial resistant to superacid compositions to form a compound havingthe following formula:M_(a)[R_(b)Z_(c)B_(d)H_(e−n)F_(y+n)]_(k)wherein M is a cation having a valence from 1-4; R is selected from thegroup consisting of a halogen group, hydroxyl group, amino group, nitrogroup, alkyl group, alkoxy group, perfluoroalkoxy group, phenyl groupand combinations thereof; Z is selected from the group consisting of C,Si, Ge, Sn, Pb, N, P, As, Sb, Bi and combinations thereof; B is boron; His hydrogen; F is fluorine; a is 1 or 2; b is an integer from 0 to 11, cis 0 or 1; d is an integer from 5 to 12; e is an integer from 1 to 12;and y is an integer from 0 to 11; k is 1, 2, or 3; and n is an integerfrom 1 to e. The fluorinated borohydride formed may also include adegree of fluorination (i.e., [y+n]) of equal to or greater than 5.

Still another aspect of the invention includes a fluorinated borohydridecontaining composition comprising hydrogen, at least one superacidadditive and a compound having the following formula:M_(a)[R_(b)Z_(c)B_(d)H_(e−n)F_(y+n)]_(k)wherein M is a cation having a valence from 1-4; R is selected from thegroup consisting of a halogen group, hydroxyl group, amino group, nitrogroup, alkyl group, alkoxy group, perfluoroalkoxy group, phenyl groupand combinations thereof; Z is selected from the group consisting of C,Si, Ge, Sn, Pb, N, P, As, Sb, Bi and combinations thereof; B is boron; His hydrogen; F is fluorine; a is 1 or 2; b is an integer from 0 to 11, cis an integer from 0 to 1; d is an integer from 5 to 12; e is an integerfrom 1 to 12; and y is an integer from 0 to 11; k is 1, 2, or 3; and nis an integer from 1 to e. The fluorinated borohydride may also includea degree of fluorination (i.e., [y+n]) of equal to or greater than 5.

Another aspect of the present invention relates to a compositionobtained by combining the aforementioned borohydride formulations and atleast one super acid.

An advantage of the present invention includes selective and controlledfluorination of borohydrides with facile, high-yielding synthesis offluorinated boron compounds of narrow and controlled degrees offluorination under reaction conditions that are industriallypracticable.

Another advantage of the present invention includes an ability toachieve high levels of fluorination of the borohydride anions.

Still another advantage of the present invention includes an ability toachieve higher yields and reaction efficiency.

Still another advantage of the present invention includes an ability toachieve high loadings of reactant in the carrier, and an ability tominimize yield loss due to byproduct formation.

Other features and advantages of the present invention will be apparentfrom the following more detailed description of certain aspects orembodiments, taken in conjunction with the accompanying drawings whichillustrate, by way of example, the principles of the invention.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a process for the fluorination of borohydridesalts, including the exemplary salts of B₁₂H₁₂ ⁻² and CB₁₁H₁₂ ⁻¹,comprising the formula M_(a)[R_(b)Z_(c)B_(d)H_(e)F_(y)]_(k) (I). Theprocess may comprise fluorination by contact with a minimum quantity nmolar equivalents of HF and at least one superacid additive (denotedherein as “SA”) to produce product compounds of the formulaM_(a)[R_(b)Z_(c)B_(d)H_(e−n)F_(y+n)]_(k) (II) and is summarized by theequation:

where M is a cation having a valence from 1-4, e.g., a proton, alkalimetal, or alkaline earth metal cation; R may include halogen, hydroxyl,amino, nitro, alkyl group, alkoxy group, perfluoroalkoxy group, orphenyl group; Z is C, Si, Ge, Sn, Pb, N, P, As, Sb, or Bi; B is boron; His hydrogen; F is fluorine; a is 1 or 2; b is an integer from 0 to 11, cis an integer from 0 to 1; d is an integer from 5 to 12; e is an integerfrom 1 to 12; y is an integer from 0 to 11; k is 1, 2, or 3, therespective values of a and k being determined by the valence of M, thatis, when the integer a is multiplied by the valence of M it is equal tothe integer k or 2 times the integer; and n is an integer from 1 to ewherein said borohydride salt compound I is contacted with HF and asuperacid under conditions for formation of the said fluorinated productcompound II. For example, salts of dodecahydrododecaborate (B₁₂H₁₂ ²⁻)can be treated with superacidic HF thereby affecting consecutivefluorinations to provide salts of B₁₂F_(x)H_(12−x) ²⁻ where x can befrom 3 to 10 and can have a distribution range of 1-3 fluorines. Themethod of the present invention is particularly suitable for preparingfluorinated compounds having higher degrees of fluorination with anarrow distribution of fluorinated products. Specifically, thefluorinated product compound II can include a degree of fluorination(i.e., [y+n]) of equal to or greater than 5, including degrees offluorination greater than or equal to 6 and degrees of fluorinationgreater than or equal to 8.

For both salt compounds I and II, M comprises a cation that may beselected based on its desired interaction with the corresponding[R_(b)Z_(c)B_(d)H_(e−n)F_(y+n)] anion, HF, or the superacid additive toaffect acidity, solubility, reaction rate, ease of isolation, degree offluorination, or other reaction system properties. Examples of M cationscomprise at least one member from the group consisting of hydrogen,hydronium (H₃O⁺), ammonium, tetraalkylammonium, trialkylammonium, alkalimetals, alkaline earth metals, tetraalkylphosphonium, and transitionmetals such as zinc, silver, iron, nickel, tantalum, and cerium.Desirable results have been obtained cations are represented byhydrogen, the alkali metals, and alkaline earth metals.

The borohydride precursor compound I as described above can berepresented by numerous compositions. The [R_(b)Z_(c)B_(d)H_(e)F_(y)]anion is represented as a polyhedral, boron-containing cluster bearingB—H bonds. The backbone of the cluster, Z and B as broadly defined aboveand represented by simple examples, such as B₁₂H₁₂ ²⁻ and CB₁₁H₁₂ ⁻, isgenerally a polyhedral core structure bearing the pendant groups R, H,and F, which may be positioned by design to affect the subsequentdesired substitution pattern of F for H.

The ability to fluorinate different forms of compound I may vary greatlydepending the actual constitution of the [R_(b)Z_(c)B_(d)H_(e)F_(y)]anion. Thus, the composition of compound I may vary since the inventionbroadly permits the more facile conversion of B—H bonds to B—F bondsthrough the use of superacidic HF as demonstrated in the Examples byfluorination of B₁₂H₁₂ ²⁻.

HF is provided as a reactant to affect the fluorination of precursorcompound I. HF may be present in amounts ranging from a stoichiometricor limiting reagent to very dilute liquid systems where HF comprisesabout 99% or greater by weight the total mass of reactants. The amountof HF is typically about 60% to about 95% by weight of the total mass ofall reactants to act as a solvent and liquid transfer medium where thegreater concentrations of HF are useful to achieve the highest degreesof fluorination. HF may also be used in the presence of a second liquidas a solvent or transfer medium; examples of such alternate liquidscomprise but are not limited to SO₂ClF, SO₂, perfluorinated liquids suchas KRYTOX® and FOMBLIN® fluids, chlorofluorocarbons,hydrochlorofluorocarbons and hydrofluorocarbons. KRYTOX® is a federallyregistered trademark of E. I. DU PONT DE NEMOURS AND COMPANYCORPORATION, Wilmington, Del. for perfluorinated liquids. FOMBLIN® is afederally registered trademark of AUSIMONT S.P.A. COMPANY, Milan, Italyfor perfluorinated liquids.

The superacid (SA) may be selected in order to enhance the acidity ofthe reaction system by complexing basic fluorides, by complexing orreacting with adventitious moisture or other basic materials such asalcohols and amines, and/or by tuning the acidity in a manner believedto affect the equilibrium of increasing or maximizing the concentrationof M associated with the anion [R_(b)Z_(c)B_(d)H_(e)F_(y)], itsintermediates and products as a proton. SA is defined as a compound ormixture of compounds capable of having an acidity or activity (e.g.,enhancing the ability to add F to the borohydride precursor) inanhydrous HF that is equal to or greater than substantially pure HF.

Examples of suitable compositions for the SA comprise but are notlimited to Lewis acids such as AlCl₃, AlF₃, BCl₃, BF₃, GaF₃, VF₅, NbF₅,TaF₅, PCl₅, PF₅, AsF₅, SbCl₅, SbF₅, BiF₅, OsF₅, ReF₅, MoF₅, WF₆ andWOF₄; mixed halogen superacids such as AlCl_(3−x)F_(x) where x can be0-3; sulfonic superacids and anhydrides such as FSO₂OH, F₃CSO₂OH, SO₃,F₃CSO₂OSO₂CF₃, and acidic NAFION® resins; other protonic acids includingthe acid forms of fluorinated polyhedral boranes and carboranes such asthe respective compositions H₂B₁₂H_(12−x)F, and HCB₁₁H_(12−x)F_(x);superacids that are generated in situ by reaction with HF or anotherfluorinating agent to include SbCl₅, BCl₃, PCl₅, and AlCl₃; and mixturesof these and other superacids and acidic melts. NAFION® is a federallyregistered trademark of E. I. DU PONT DE NEMOURS AND COMPANYCORPORATION, Wilmington, Del. for resin compositions. The choice ofsuperacid will depend upon the precursor compound I, the degree offluorination desired, any safety considerations, and any requirements toavoid side reactions or improve yields. For example, the superacid canbe non-oxidizing to the anion [R_(b)Z_(c)B_(d)H_(e)F_(y)] and itsproducts. The superacid may be present as a catalyst, as astoichiometric reagent, or in an amount excess relative to the precursorI.

Examples of compounds which can be formed by the instant invention cancomprise at least one member selected from the group consisting of alithium fluorododecaborates of the formula:Li₂B₁₂F_(x)Z_(12−x)where x is greater than or equal to 4 or 5 (average basis), typically atleast 8, and in some cases at least 10 but less than or equal to 12, andZ represents H, Cl, and Br. Specific examples of lithium basedfluorinated dodecaborates can comprise at least one member from thegroup consisting of: Li₂B₁₂F₅H₇, Li₂B₁₂F₆H₆, Li₂B₁₂F₇H₅, Li₂B₁₂F₈H₄,Li₂B₁₂F₉H₃, Li₂B₁₂F₁₀H₂, Li₂B₁₂F₁₁H, Li₂B₁₂F₁₂ and mixtures of saltswith varying x such that the average x is equal to or greater than 5, orequal to 9 or 10, or Li₂B₁₂F_(x)Cl_(12−x) and Li₂B₁₂F_(x)Br_(12−x) wherex is 10 or 11.

The reactants may be combined in any order and at any rate to affect thedesired fluorination chemistry, however, in some cases it may be usefulto provide one or both of precursor compound I and SA diluted in HF oranother solvent to affect safety and or process control factors as canbe developed though good practices in chemistry and engineering.

The materials of construction for the reactor, as apparent to thoseskilled in the art, will have a role in the effectiveness of thisinvention as it pertains to the use of classically defined superacids. Areactor fabricated with components selected from copper, gold, aluminum,nickel, silver, platinum, palladium, carbon, TEFLON® resins,polyvinylchloride resins, polychlorotrifluoroethylene (e.g., KEL-F®)resins, hydrocarbon thermoplastics, sapphire, boron carbide, tantalumnitride, steel alloys, MONEL® alloys, HASTELLOY® alloys, and othersimilar materials would be suitable to observe the general advantagesoutlined in this invention. HASTELLOY® is a federally registeredtrademark of HAYNES INTERNATIONAL, INC., Kokomo, Ind. for alloycompositions. MONEL® is a federally registered trademark of HUNTINGTONALLOYS CORPORATION, Huntington, WV. In some cases, the contact surfacesof the reactor can be composed of a form of TEFLON®, KEL-F®, sapphire,tantalum nitride, MONEL® alloy 400, MONEL® alloy 200, or HASTELLOY® Calloy 276 in order to enable the higher degrees of fluorination andpreserve the reactor components from etching especially at highertemperatures and when stronger superacids are employed. KEL-F® is afederally registered trademark of MINNESOTA MINING AND MANUFACTURINGCOMPANY CORPORATION, St. Paul, Minn. for polychlorotrifluoroethyleneresins. TEFLON® is a federally registered trademark of E. I. DU PONT DENEMOURS AND COMPANY CORPORATION, Wilmington, Del. forpolytetrafluoroethylene products.

The following examples are provided to illustrate certain aspects of theinvention and do not limit the scope of the claims appended hereto. Massbalance, mass spectrometry and NMR were used in accordance withconventional methods to detect the reaction products referenced below.

EXAMPLES

A reaction mixture for fluorination of boron hydrides was prepared. BF₃and HF were supplied by Air Products & Chemicals, Inc. (Allentown, Pa.).TaF₅ and SbF₅ were obtained from Sigma-Aldrich (Milwaukee, Wis.) andwere treated with a mixture of F₂ and N₂ gases (AiroPak, Air Products &Chemicals) to remove moisture and/or oxygenated materials. Potassiumdodecahydrododecaborate methanolate (K₂B₁₂H₁₂—MeOH, Callery ChemicalCo., Pittsburgh, Pa.) was treated to remove methanol. Tetraethylammoniumbromide was obtained from Sigma-Aldrich. Water in the examples isdeionized water unless otherwise indicated. Reactors were cleaned toremove contaminants then were vacuum-dried and F₂ passivated prior touse. HF and BF₃ were transferred into a reactor vessel at −78° C. Thecharged reactors were allowed to warm to ambient temperature (e.g.,20-25° C.) then heated to the desired temperature for the desired amountof time. Following each reaction the reactor contents were cooled toroom temperature, volatile components were evacuated and the crudeproduct was rinsed from the reactor with water. The rinsate wasneutralized to pH 12-13 and filtered. In all cases a clear, colorlesssolution was obtained as a filtrate to which an excess of aqueoustetraethylammonium (“TEA”) bromide was added to precipitate the productas a fine powder that was captured by filtration. The filter cake wasrinsed with warm water to remove impurities until the pH of the filtratebecame substantially neutral. The solid product was then vacuum dried.

Comparative Example 1 Reaction of K₂B₁₂H₁₂ with HF at 20° C. inStainless Steel

1.00 g of K₂B₁₂H₁₂ (220.02 g/mol, 4.5 mmol) was charged to a 100 mL SSParr reactor followed by 20 g of HF at −78° C. The reactor was warmed to20° C. and was allowed to stir for 16 hours. Following the removal of HFunder vacuum the product was purified and analyzed as outlined aboveproviding 1.89 g (ca. 91% yield) of (tetraethylammonium (TEA))₂B₁₂H₉F₃(MW_(ave)=456.30 g/mol). Percentages are on a weight basis, unlessspecifically indicated otherwise.

Comparative Example 2 Reaction of K₂B₁₂H₁₂ with HF at 20° C. in aTeflon-Lined Vessel

Comparative Example 1 was repeated except using a Hastalloy C-276 Parrreactor with TEFLON® liner in place of the stainless steel reactor. Theisolated product consisted of 1.91 g (ca. 92% yield) of product(TEA)₂B₁₂H_(12−x)F_(x) with 93 mol % (i.e., percentage on a molar basis)where x=3 and 7 mol % where x=4 (MW_(ave)=474.29 g/mol).

Example 1 Reaction of K₂B₁₂H₁₂ with HF and BF3 at 20° C. in StainlessSteel

1.00 g of K₂B₂₁H₁₂ (220.02 g/mol, 4.5 mmol) was charged to a 100 mL SSParr reactor followed by 20 g of HF at −78° C. The reactor was warmed to20° C. and was allowed to stir for 16 hours. BF₃ (ca. 18 mmol, 4equivalents relative to K₂B₁₂H₁₂) was added to the reactor following HFaddition. The product was then isolated and found to have 1.95 g (ca.90% yield) of product (TEA)₂B₁₂H_(12−x)F_(x) with 84 mol % where x=4 and16 mol % where x=5 (MW_(ave)=492.28 g/mol).

Example 2 Reaction of K₂B₁₂H₁₂ with HF and Excess BF₃ at 20° C. inStainless Steel

Example 1 was repeated except 45 mmol BF₃ (ca., 10 equivalents relativeto K₂B₁₂H₁₂) was added to the reactor following HF addition rather than18 mmol BF₃. The isolated product consisted of 1.95 g (ca. 88% yield) ofproduct (TEA)₂B₁₂H_(12−x)F_(x) with 29 mol % where x=4, 70 mol % wherex=5, and approximately 1 mol % where x=6 (MW_(ave)=510.27 g/mol).

Example 3 Reaction of K₂B₁₂H₁₂ with HF and BF₃ at 60° C. in StainlessSteel

Example 1 was repeated except at 60° C. as a reaction temperature ratherthan 20° C. The isolated product consisted of 2.09 g (ca. 90% yield) ofproduct (TEA)₂B₁₂H_(12−x)F_(x) with 3 mol % where x=5, 95 mol % wherex=6, and 2 mol % where x=7 (MW_(ave)=528.26 g/mol).

Example 4 Reaction of K₂B₁₂H₁₂ with HF and BF₃ at 120° C. in StainlessSteel

Example 1 was repeated except at 120° C. as a reaction temperaturerather than 20° C. The crude material isolated from the reactorpossessed considerable color indicating leaching of iron and/orchromium. The isolated product consisted of 1.94 g (ca. 81% yield) ofproduct (TEA)₂B₁₂H_(12−x)F_(x) with 3 mol % where x=6, 94 mol % wherex=7, and 3 mol % where x=8 (MW_(ave)=546.25 g/mol).

Example 5 Reaction of K₂B₁₂H₁₂ with HF and Excess BF₃ at 120° C. inStainless Steel

Example 2 was repeated except at 120° C. as a reaction temperaturerather than 20° C. The crude material isolated from the reactorpossessed considerable color indicating leaching of iron and/orchromium. The isolated product consisted of 1.84 g (ca. 77% yield) ofproduct (TEA)₂B₁₂H_(12−x)F_(x) with 8 mol % where x=6, 91 mol % wherex=7, and approximately 1 mol % where x=8 (Mw_(ave)=546.25 g/mol).

Example 6 Reaction of K₂B₁₂H₁₂ with HF and BF₃ at 120° C. in aTEFLON®-Lined Vessel

Example 5 was repeated except using a Hastalloy C-276 Parr reactor withTEFLON® liner in place of the stainless steel reactor. The isolatedproduct consisted of 2.18 g (ca. 89% yield) of product(TEA)₂B₁₂H_(12−x)F_(x) with 38 mol % where x=7, 62 mol % where x=8.

Example 7 Reaction of K₂B₁₂H₁₂ with HF and Catalytic BF₃ at 120° C. in aTEFLON®-Lined Vessel

Example 6 was repeated except 2.5 mmol BF₃ (ca., 0.6 equivalentsrelative to K₂B₁₂H₁₂) were added to the reactor following HF additionrather than 18 mmol BF₃. The isolated product consisted of 2.19 g (ca.90% yield) of product (TEA)₂B₁₂H_(12−x)F_(x) with 58 mol % where x=7,and approximately 42 mol % where x=8.

Example 8 Scaled Reaction of K₂B₁₂H₁₂ with HF and Catalytic BF₃ at 120°C. in a TEFLON®-Lined Vessel

5.00 g of K₂B₁₂H₁₂ (23 mmol) were charged to a 300 mL Hastalloy C-276Parr reactor with TEFLON® liner followed by 100 g of HF and BF₃ (ca.13.8 mmol, 0.6 equivalents relative to K₂B₁₂H₁₂) at −78° C. The reactorwas warmed to 20° C. then was heated to 120° C. and held at 120° C. for16 hours. Following the removal of HF under vacuum the product waspurified and analyzed as outlined above providing 10.52 g (ca. 86%yield) of product (TEA)₂B₁₂H_(12−x)F_(x) with 45 mol % where x=7 and 55mol % where x=8.

Example 9 Reaction of K₂B₁₂H₁₂ with HF and TaF₅ at 20° C. in afluorinated ethylene propylene (FEP) Tube

A Teflon tee was fitted with a valve and 2 FEP reaction tubes. 0.20 g ofK₂B₁₂H₁₂ (0.9 mmol) were charged to one FEP tube and 1.00 g of TaF₅(275.94 g/mol, 3.6 mmol, 4 equivalents relative to K₂B₁₂H₁₂) were loadedto the other FEP tube. 4 g of HF were added to the tube containingK₂B₁₂H₁₂ at −78° C. and the TaF₅ was allowed to deliquesce with HF vaporat room temperature. The reactor was allowed to warm to 20° C duringwhich H₂ gas evolution was observed. After 2 hours the gas evolution hadceased and the TaF₅—HF solution was slowly poured into the tubecontaining the borate salt giving rise to immediate and vigorousevolution of additional H₂. The reactor contents were allowed to standfor 16 hours maintaining a clear and colorless solution throughoutindicating that TaF₅ was not reduced. Following the removal of HF undervacuum the product was purified and analyzed as outlined above providing0.43 g (ca. 86% yield) of product (TEA)₂B₁₂H_(12−x)F_(x) with 10 mol %where x=5 and 90 mol % where x=6.

Comparative Example 3 Reaction of K₂B₁₂H₁₂ with HF and TaF₅ at 60° C. inStainless Steel

1.00 g of K₂B₁₂H₁₂ (4.5 mmol) and 4.92 g of TaF₅ (18 mmol, 4 equivalentsrelative to K₂B₁₂H₁₂) were carefully charged to a 100 mL stainless steelParr reactor followed by 20 g of HF at −78° C. The reactor was warmed to20° C. then was heated to 60° C. with stirring for 16 hours. Followingthe removal of HF under vacuum the product was purified and analyzed asoutlined above providing 1.58 g (ca. 69% yield) of product(TEA)₂B₁₂H_(12−x)F_(x) with 45 mol % where x=5, 54 mol % where x=6, andapproximately 1 mol % where x=7. The crude product possessed a deepgreen color indicating the presence of iron and/or chromium and thesurfaces of the reactor were observed to be pitted.

Comparative Example 4 Reaction of K₂B₁₂H₁₂ with HF and TaF₅ at 120° C.in Stainless Steel

Comparative Example 3 was repeated except at 120° C. as a reactiontemperature rather than 60° C. The isolated product consisted of 1.21 g(ca. 52% yield) of product (TEA)₂B₁₂H_(12−x)F_(x) with 89 mol % wherex=6, 11 mol % where x=7. The crude product possessed a deep colorappearing black and pitting to the reactor surfaces damaged the reactorbeyond repair.

Example 10 Reaction of K₂B₁₂H₁₂ with HF and TaF₅ at 120° C. in aTeflon-Lined Vessel

The steps of Comparative Example 4 were repeated except using aHastalloy C-276 Parr reactor with teflon liner in place of the stainlesssteel reactor. The isolated product consisted of 2.17 g (ca. 87% yield)of product (TEA)₂B₁₂H_(12−x)F_(x) with 80 mol % where x=8 and 20 mol %where x=9 (MW_(ave)=564.24 g/mol). The crude product contained a smallamount of a black solid indicating the potential reduction of a tinyquantity of TaF₅.

Comparative Example 5 Reaction of K₂B₁₂H₁₂ with HF and SbF₅ at 20° C. inan FEP Tube

A Teflon tee was fitted with a valve and 2 FEP reaction tubes. 0.20 g ofK₂B₁₂H₁₂ (0.9 mmol) were charged to a one FEP tube followed by 4 g of HFat −78° C. The reactor contents were allowed to warm to 20° C. andevolve H₂ for 2 hours. After removing the HF, 0.90 g of SbF₅ (216.75g/mol, 4.2 mmol, 4.5 equivalents relative to K₂B₁₂H₁₂) were loaded tothe empty FEP tube. 4 g of HF were added to the tube containing theborate salt at −78° C. and the SbF₅ absorbed HF vapor at roomtemperature. The reactor were warmed to 20° C. and the SbF₅−HF solutionwas slowly poured into the tube containing the borate salt solutionproducing immediate precipitation of colorless solids throughout theaddition but no H₂ gas evolution. The reactor contents were allowed tostand for 16 hours. Following the removal of HF under vacuum the productwas purified and analyzed as outlined above providing 0.40 g (ca. 80%yield) of product (TEA)₂B₁₂H_(12−x)F_(x) with 8 mol % where x=7, 32 mol% where x=8, 55 mol % where x=9, and 5 mol % where x=10 (MW_(ave)=582.23g/mol). The cascading distribution of fluorinated products and reactionprecipitate in this example indicate that SbF₅ may be primarily actingas an oxidative fluorinating agent rather than a superacid.

While the invention has been described with reference to a certainaspects or embodiment, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A process for fluorination of borohydride salts comprising: providinga reaction medium comprising HF and at least one superacid additive;providing a borohydride salt compound to the reaction medium having thefollowing formula:M_(a)[R_(b)Z_(c)B_(d)H_(e)F_(y)]_(k) wherein M is a cation having avalence from 1 to 4; R is selected from the group consisting of ahalogen group, hydroxyl group, amino group, nitro group, alkyl group,alkoxy group, perfluoroalkoxy group, phenyl group and combinationsthereof; Z is selected from the group consisting of C, Si, Ge, Sn, Pb,N, P, As, Sb, Bi and combinations thereof; B is boron; H is hydrogen; Fis fluorine; a is 1 or 2; b is an integer from 0 to 11, c is an integerfrom 0 to 1; d is an integer from 5 to 12; e is an integer from 1 to 12;and y is an integer from 0 to 11; k is 1, 2, or 3; and reacting theborohydride salt with the reaction medium under conditions for formationof a fluorinated borohydride salt having the formula:M_(a)[R_(b)Z_(c)B_(d)H_(e−n)F_(y+n)]_(k) wherein n is an integer from 1to e and y+n is greater than or equal to
 5. 2. The process of claim 1,wherein the M cation comprises at least one member selected from thegroup consisting of a hydrogen, alkali metal, and alkaline earth metal.3. The process of claim 1, wherein the M cation comprises at least onemember selected from the group consisting of hydrogen, hydronium (H₃O⁺),ammonium, tetraalkylammonium, trialkylammonium, alkali metals, alkalineearth metals, tetraalkylphosphonium, and transition metals such as zinc,silver, iron, nickel, tantalum, and cerium.
 4. The process of claim 1,wherein b and c are
 0. 5. The process of claim 1, wherein d is aninteger selected from the group consisting of 10 and
 12. 6. The processof claim 1, wherein the superacid additive comprises at least one memberselected from the group consisting of AlCl₃, AlF₃, BCl₃, BF₃, GaF₃, VF₅,NbF₅, TaF₅, PCl₅, PF₅, AsF₅, SbCl₅, SbF₅, BiF₅, OsF₅, ReF₅, MoF₅, WF₆,WOF₄, mixed halogen superacids, sulfonic superacids and anhydrides,protonic acids, superacid reaction products of HF or anotherfluorinating agent and SbCl₅, BCl₃, PCl₅, or AlCl₃ and combinationsthereof.
 7. The process of claim 1, wherein the reaction medium furtherincludes a transfer medium.
 8. The process of claim 1, wherein thetransfer medium comprises at least one member selected from the groupconsisting of SO₂ClF, SO₂, perfluorinated liquids, chlorofluorocarbons,and hydrofluorocarbons.
 9. The process of claim 1, wherein the reactingstep takes place at a temperature of less than about 120° C.
 10. Aprocess for fluorination of borohydride salts comprising: fluorinating aborohydride salt compound having the following formula:M_(a[R) _(b)Z_(c)B_(d)H_(e)F_(y)]_(k) in the presence of at least onesuperacid additive and HF in a reactor vessel fabricated from a materialresistant to superacid compositions to form a compound having thefollowing formula:M_(a)[R_(b)Z_(c)B_(d)H_(e−n)F_(y+n)]_(k) wherein M is a cation having avalence from 1 to 4; R is selected from the group consisting of ahalogen group, hydroxyl group, amino group, nitro group, alkyl group,alkoxy group, perfluoroalkoxy group, phenyl group and combinationsthereof; Z is selected from the group consisting of C, Si, Ge, Sn, Pb,N, P, As, Sb, Bi and combinations thereof; B is boron; H is hydrogen; Fis fluorine; a is 1 or 2; b is an integer from 0 to 11, c is an integerfrom 0 to 1; d is an integer from 5 to 12; e is an integer from 1 to 12;and y is an integer from 0 to 11; k is 1, 2, or 3; and n is an integerfrom 1 to e and y+n is greater than or equal to
 5. 11. The process ofclaim 10, wherein the reactor vessel is fabricated from at least onematerial selected from the group consisting of copper, gold, aluminum,nickel, silver, platinum, palladium, carbon, polytetrafluoroethyleneresins, polyvinylchloride resins, polychlorotrifluoroethylene resins,hydrocarbon thermoplastics, sapphire, boron carbide, tantalum nitride,steel alloys, superalloys, and combinations thereof.
 12. The process ofclaim 10 wherein the M cation comprises at least one member selectedfrom the group consisting of a hydrogen, alkali metal, and alkalineearth metal.
 13. The process of claim 10, wherein the M cation comprisesat least one member selected from the group consisting of hydrogen,hydronium (H₃O⁺), ammonium, tetraalkylammonium, trialkylammonium, alkalimetals, alkaline earth metals, tetraalkylphosphonium, and transitionmetals such as zinc, silver, iron, nickel, tantalum, and cerium.
 14. Theprocess of claim 10, wherein b and c are
 0. 15. The process of claim 10,wherein d is an integer selected from the group consisting of 10 and 12.16. The process of claim 10, wherein the superacid additive comprises atleast one member selected from the group consisting of AlCl₃, AlF₃,BCl₃, BF₃, GaF₃, VF₅, NbF₅, TaF₅, PCl₅, PF₅, AsF₅, SbCl₅, SbF₅, BiF₅,OsF₅, ReF₅, MoF₅, WF₆, WOF₄, mixed halogen superacids, sulfonicsuperacids and anhydrides, protonic acids, superacid reaction productsof HF or another fluorinating agent and SbCl₅, BCl₃, PCl₅, or AlCl₃, andcombinations thereof.
 17. The process of claim 10, wherein the reactingstep takes place at a temperature of less than about 120° C.
 18. Theprocess of claim 10 wherein the compound comprises Li₂B₁₂F_(x)Z_(12−x)where x is less than or equal to 12, and Z represents H, Cl, and Br.